108 Krug von Nidda on the Mineral Springs of Iceland. 



stances, and then united with the atmospheric water, still these 

 explanations do not at most account for more than the carbonic 

 acid of ordinary spring water, and by no means for the great 

 disengagements of carbonic acid which are found at many parts 

 of the earth's surface, and in which the gas is either combined 

 with water, or issues from the ground in a free condition. 



If we do not regard it as accidental, that all the great disen- 

 gagements of carbonic acid gas, and further that most mineral 

 waters occur in the vicinity, and in the district of active vol- 

 canos, or of such rocks as have undoubtedly been formed by 

 volcanic agency ; and as we find that the same ingredients 

 which mineral waters contain in solution predominate in the 

 products of active volcanos ; we cannot doubt of the connection 

 in which mineral waters stand with the pi utonic processes of our 

 globe. But how these acids of mineral waters were produced 

 in the seats of volcanic fire ; whether in their place of origin they 

 were already united with the bases of the salts with which they 

 are combined in the mineral waters ; or whether they derived 

 these bases from the rocky masses, that they encountered du- 

 ring their passage to the earth's surface ; are questions which 

 can only be answered hypothetically. 



If the simple structure of the island of Iceland presents us 

 with a display of the gigantic power, which has elevated the 

 trachyte to lofty and widely extending plateaus, raised enor- 

 mous trap mountains from the depths of the ocean to vast 

 heights, and torn asunder these mountains by means of fis- 

 sures of frightful depth and great length ; if the eruptions of 

 the volcanos, and the streams of fire from their open summits, 

 which have covered whole districts, and the shocks of earth- 

 quakes which shake the island to its very foundations, leave no 

 doubt of the prodigious extent of the subterranean fires ; the 

 mineral springs which are the feeblest indications of volcanic ac- 

 tivity, afford perhaps the most important information as to the 

 substances contained in the interior of our planet, and as to the 

 processes to which they are subjected. 



The analyses of the Geyser water have only informed us of those 

 ingredients which remain as solid component parts after evapo- 

 ration, but not of those substances which escape in a gaseous 

 form during evaporation. We have said already that the water 



